The present invention relates to a multilayer product, called xe2x80x9cMultipurxe2x80x9d, its use for the production of light, acoustic-insulated, self-supporting articles and the articles obtained with said multilayer product.
A typical application of the multilayer product according to the present invention is represented by all lining and fitting elements of car interiors such as for example the self-supporting lining for the cabin roof, or quite simply cabin, the door panels, rear shelf, boot or hatch back-door linings, jamb covers, sun-shields and generally all lining and fitting elements of car interiors, for which certain requisites must be satisfied such as lightness, self-supporting properties (i.e. the capacity of supporting its own weight, without the need for supporting structures), acoustic insulation and/or flexibility.
Light materials for the production of articles, in particular lining and fitting elements of car interiors, by means of a hot moulding process, are known in literature. A known material, light and mouldable, for the above use consists, for example, of a xe2x80x9csandwichxe2x80x9d product which comprises a layer of polyurethane inserted between two layers of fibre glass and/or natural fibre impregnated with polyurethane resin; the two layers of fibre glass and resin, also called xe2x80x9cmatxe2x80x9d, are coupled in continuous with the central layer consisting of polyurethane. Outside the layer of fibre glass and/or natural fibre and resin, there can also be other layers of light materials, glue or other fabric: the sandwich-structured sheet thus obtained, is subsequently hot moulded to obtain the desired element.
In particular, the glass fibre and/or natural fibre impregnated with thermo-sensitive polyurethane resin, is coupled in continuous on both surfaces of the polyurethane layer, causing the formation of a so-called sandwich.
The sandwich thus obtained, optionally also coupled with other layers of light fabric and/or other materials, is sent to the hot moulds where the desired article is produced.
The product thus obtained, although it has good lightness, self-supporting and acoustic-insulation properties, demonstrates uniformity of characteristics. This means that in every point of the structure subjected to hot moulding treatment, it has analogous lightness, acoustic-insulation and self-supporting properties.
This results in an inadequate adaptability inside the vehicle where it is necessary to have more rigid areas, with a minimum thickness, and less rigid areas with any thickness. In addition, there are areas in which the acoustic insulation is particularly necessary and areas where this characteristic is less desirable.
Furthermore, with the improvement of supply techniques, car manufacturers require that the products supplied, already pre-assembled, have additional components such as, for example; handles, sun-shields, light panels, etc.; under these conditions, the traditional products, obtained with the methods known in literature, have considerable problems relating to movement breakage, due to their limited mechanical strength.
The objective of the present invention is to identify a product which allows the drawbacks of the known art to be overcome and in particular to obtain an article in which there are extremely rigid zones and also zones which are still flexible.
The Applicant has surprisingly found that by using a particular type of multilayer product, it is possible to produce elements having areas with different physico-chemical characteristics.
In the case of a car cabin, for example, the multilayer product according to the present invention allows the production of an article in which the lateral parts are flexible and allow the expulsion of lateral air-bags situated between the roof and lining of the cabin, whereas the central part is extremely rigid and allows the positioning of light panels, switches, sunshields, etc.
An object of the present invention therefore relates to a multilayer product which comprises a first element consisting of a layer of spongy, semi-rigid polymer (A), impregnated on one or both sides with polyurethane resin (B), and inserted between two layers of glass fibre and/or natural fibre (C), coupled in continuous with the central layer (B) (A) (B), said first element being characterized in that it is coupled with at least a second element comprising a layer of spongy, semi-rigid polymer (A), impregnated on one or both sides with polyurethane resin (B), said second element being in turn coupled with a further layer of glass fibre and/or natural fibre (C).
The multilayer product according to the present invention therefore has a (B) (A) (B) (C) (B) (A) (B) structure, wherein A, B and C have the meanings defined above and wherein other elements consisting of the layers (A), (B) and (C), can be added to the outer sides of this structure, with the alternation specified above, and/or with different alternations.
In particular, in the multilayer product thus obtained, the spongy, semi-rigid polymer can be selected from polyurethane, polystyrene, polyester.
The spongy, semi-rigid polymer is preferably polyurethane.
It is even more preferably a polyurethane obtained by the reaction between a polyol and isocyanate with a density varying from 20 to 40 kg/m3.
The polymer which forms the layer (A) can be the same in all the (A) layers or each (A) layer can be produced with a polymer which has different densities and different thicknesses.
The glass fibre can also be substituted by another natural fibre such as jute, sisal, coir or other equivalent materials.
The structure of the multilayer product according to the present invention (C) (B) (A) (B) (C) (B) (A) (B) (C) comprises the coupling, on the two outer sides of the coupled elements, of layers of light fabrics and/or covering vlies (D), thus obtaining a product with the following structure: (D) (C) (B) (A) (B) (C) (B) (A) (B) (C) (D).
The multilayer product thus obtained may also comprise the application on both outer sides of the sandwich, i.e. of the elements already coupled, or on only one of these, lining fabric, layers of anti-vibration material, etc.
The thickness of the layer (A) can vary from 4 to 18 mm and preferably from 5 to 7 mm.
The thickness of the layer (A) is even more preferably equal to 6 mm.
The layers of spongy, semi-rigid polymer (A) present in the multilayer product according to the present invention can have the same thickness or different thicknesses.
A further object of the present invention relates to the use of the multilayer product according to the present invention for the production of light, self-supporting, acoustic-insulated articles.
The present invention also relates to light, self-supporting, acoustic-insulated articles obtained by means of the hot moulding of the multilayer product according to the present invention.
In particular, these articles are lining or fitting elements of car interiors.
The present invention also relates to a process for the processing of the multilayer product, said process being characterized by applying different pressure concentrations in the different zones of the multilayer product, thus obtaining areas having different compression strength, flexibility and acoustic-insulation properties.
The main advantage of the multilayer product according to the present invention is that it allows the production of articles, in particular all lining and fitting elements for car interiors, having different flexibility and flexural strength properties depending on the various areas of the end-product.